<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      width: 100px;
      height: 100px;
      background-color: rgba(17, 119, 255, 0.5);

      /* margin: (上右下左); */
      /* margin: 5px; */

      /* margin: (上下) (右左); */
      /* margin: 5px 10px; */

      /* margin: (上) (右左) (下); */
      /* margin: 5px 10px 20px; */

      /* margin: (上) (右) (下) (左); */
      /* margin: 5px 10px 20px 40px; */

      /* 单方向 margin */
      margin-top: 5px;
      margin-bottom: 5px;
      margin-left: 5px;
      margin-right: 5px;
    }
  </style>
</head>

<body>
  <div></div>
</body>

</html>